1. Field of the Invention
The present invention relates to a portable terminal comprising an organic electroluminescence (the “electroluminescence” will be hereinafter referred to as “EL”) display device and an organic EL display device.
2. Description of the Related Art
FIG. 1 shows the structure of a conventional organic EL display device. In FIG. 1, 41 denotes a glass substrate, 42 denotes an anode, 43 denotes a cathode and 44 denotes an organic EL layer. In the organic EL display device, the anode 42, the organic EL layer 44 and the cathode 43 are provided on the upper surface of the transparent glass substrate 41.
In order to operate the conventional organic IL display device, a dc voltage or a signal voltage is applied between the anode 42 and the cathode 43 to carry out EL light emission through the organic EL layer 44.
With the structure of the conventional organic EL display device, the organic EL layer is constituted by only one layer. Therefore, an emission luminance is obtained in accordance with a quantum efficiency caused by the material and structure of the organic EL layer.